I am using pandas.read_sql function with hive connection to extract a really large data. I have a script like this:
df = pd.read_sql(query_big, hive_connection)
df2 = pd.read_sql(query_simple, hive_connection)
The big query take a long time, and after it is executed, python returns the following error when trying to execute the second line:
raise NotSupportedError("Hive does not have transactions") # pragma: no cover
It seems there is something wrong with the connection.
Moreover, If I replace the second line with multirpocessing.Manager().Queue(), It returns the following error:
File "/usr/lib64/python3.6/multiprocessing/managers.py", line 662, in temp
token, exp = self._create(typeid, *args, **kwds)
File "/usr/lib64/python3.6/multiprocessing/managers.py", line 554, in _create
conn = self._Client(self._address, authkey=self._authkey)
File "/usr/lib64/python3.6/multiprocessing/connection.py", line 493, in Client
answer_challenge(c, authkey)
File "/usr/lib64/python3.6/multiprocessing/connection.py", line 732, in answer_challenge
message = connection.recv_bytes(256) # reject large message
File "/usr/lib64/python3.6/multiprocessing/connection.py", line 216, in recv_bytes
buf = self._recv_bytes(maxlength)
File "/usr/lib64/python3.6/multiprocessing/connection.py", line 407, in _recv_bytes
buf = self._recv(4)
File "/usr/lib64/python3.6/multiprocessing/connection.py", line 383, in _recv
raise EOFError
EOFError
It seems this kind of error are related to exit function being messed up, in the connection.py. Moreover, when I changed the query in the first command to extract smaller data that doesn't take too long, Everything works fine. So I assume it may be that because it takes too long to execute the first query, something is improperly terminated. which caused the two error, both of which are so different in nature but both are related to broken connection issues.
